This is a request for renewal of my K05 Senior Scientist Award. During the past fifteen years important developments in the field of cannabinoid research have placed it in the center of biomedical research. The K05 Award has allowed me to enhance my scientific activities in this field. It has also facilitated expansion of my mentorship activities, including those directed towards under-represented minorities. Renewal of the Award will make it possible for me to continue this highly productive effort. It will allow me to regularly modernize techniques being used in my laboratory and introduce novel, state of the art technologies, including: a) the use of liquid chromatography/mass spectroscopy (LC/MS) methods for studying the structure of the GPCRs; b) the use of LC/MS methods in projects on targeted proteomics and targeted metabolomics; c) the use of molecular biological and genomics approaches to characterize and modify known endocannabinoid targets, and search for novel ones; d) the continued use of novel multidimensional NMR techniques (liquids and solids) to study key endocannabinoid proteins and their interactions with cannabinergic ligands, and e) the continued development of novel in vivo imaging approaches. The proposed research is directed towards understanding the molecular bases of cannabinoid activity, many of which are elicited through the endogenous cannabinoid biochemical system. This involves two families of endogenous ligands (endocannabinoids) represented by anandamide and 2-arachidonoylglycerol (2-AG), both of which induce their physiological responses by interacting with the two known cannabinoid receptors (CB1 and CB2). Endocannabinoid signaling is also modulated by the biochemical processes involved in the deactivation of endocannabinoid ligands, including the two known hydrolytic enzymes, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MGL), the oxidative enzyme cycloxygenase 2 (COX2) and cellular anandamide reuptake processes that remain to be fully characterized. My research program will continue to focus on understanding the structural requirements involved in the interactions of cannabinergic ligands with each of the target proteins. Such information will be utilized in the design of novel first generation ligands and improved later generation analogs. These compounds can serve as medications to treat drug abuse and assist in the resolution of this important public health problem. The work proposed under this Award will involve a multifaceted approach involving ligand design and synthesis, biophysical and computational chemistry, and biochemical experiments. The results should reveal the molecular properties required for cannabinergic activity (the pharmacophore requirements), and assist in the design of more effective ligands which can serve as useful pharmacological tools, imaging agents, or candidate medications to treat addictive disorders and other illnesses.